The microorganism population of a flour-containing semifinished product (such as dough) is reduced by forming a suspension of flour with a liquid (particularly water, milk and/or the flowable ingredients of eggs), and subjecting the suspension to the action of an inert gas (such as carbon dioxide gas) for a period of between approximately 5 and 240 minutes at a pressure of between approximately 2 and 100 bars. The thus obtained semifinished product can be stored for extended periods of time in a standard refrigerator rather than only in a freezer. The method can further comprise the step or steps of stirring the suspension for the purposes of homogenization and/or abruptly reducing the pressure of gas upon elapse of the interval of 5-240 minutes and/or repeatedly varying the pressure of gas and/or adding to the suspension an animal and/or vegetable fat and/or adding to the suspension salt, sugar, an aromatic substance and/or another additive.